Perester free radical initiator for graft polymerization

ABSTRACT

A polyolefin graft polymer is prepared by the graft polymerization of at least one ethylenically unsaturated monomer onto a polyolefin using a perester free radical initiator selected from the group consisting of t-butyl 2ethylperhexanoate, t-amyl 2-ethylperhexanoate, t-butyl 3,5,5trimethylperhexanoate, t-amyl 3,5,5-trimethylperhexanoate, tbutyl 2-ethylperbutyrate, t-amyl 2-ethylperbutyrate, t-butyl perisobutyrate and t-amyl periso butyrate.

United States Patent H 1 [111 3,728,417 Knaack 5] Apr. 17, 1973 [54]PERESTER FREE RADICAL INITIATOR 2,858,326 10/1958 Ashby ..260/453 FORGRAFT POLYMERIZATI N 0 FOREIGN PATENTS OR APPLICATIONS [75] Inventor:Donald F. Knaack, Wilmington, Del.

1,198,067 8/1965 Germany [73] Assignee: Avisum Corporation,Philadelphia,

Primary Examiner-Harry Wong, Jr. [22] Filed; 5, 1968 Attorney-Roger V.N. Powelson, Arthur G. Gilkes,

Charles E. Feeny and John C. Martin, Jr. [21] App1.No.: 781,573

[57] ABSTRACT [52] US. Cl. 260/878, 260/296, 260/326, A polyolefin graftpolymer is prepared by the ft 260/328 260/334 260/896 260/897polymerization of at least one ethylenically unsatu- [51] Int. Cl...C08f 15/04 rated monomer onto a l l fi using a pet-ester f [58] Fieldof Search ..260/878 radical initiator l d f the group consisting oft-butyl Z-ethyIperhexanoate, t-amyl Z-ethylperhex- [56] References C'tedanoate, t-butyl 3,5,S-trimethylperhexanoate, t-amyl UNn-EDSTATES'PATENTS 3,5,S-trimethylperhexanoate, t-butyl 2-eth'y1nerbutyrate,t-amyl Z-ethylperbutyrate, t-butyl perisobu- 3,049,507 8/1962 Stanton eta]. ..260/45.5 tyrate and t-amyl periso butyrate. 3,073,667 1/1963Bonvicini et a1 ..8/115.5 3,322,712 5/1967 Gardner et a1. ..260/29.6 10Claims, N0 Drawings BACKGROUND OF THE INVENTION This invention relatesto a method of preparing graft polymerized polyolefins having improveddye receptivity and particularly to polyolefins containing crystallinepolypropylene.

It is well known that hydrocarbon polymers of the non-aromatic type arevery difficult to dye. Ample evidence is available in the technicalliterature that illustrates the fact that polyolefins exhibit little orno receptivity for dyestuffs when conventional procedures are employed.Several approaches have been proposed to remedy the problem of poor dyecharacteristics of polyolefins. One method involves the preparation ofgraft copolymers wherein a dyeable polymer such as vinyl pyridine hasbeen grafted onto a polyolefin backbone. This technique is described inUS. Pat. Nos. 3,049,508 and 3,073,667. Another approach is to prepare ablend of a polyolefin and a polymer that is more dyeable than thepolyolefin such as a vinyl pyridine homopolymer and this method isdescribed in U.S. Pat. No. 3,315,014.

An improved polyolefin composition has been obtained by the practice ofthis invention wherein a monoethylenically unsaturated, heterocyclic,nitrogencontaining monomer either alone or together with one or moreother ethylenically unsaturated monomers is grafted onto a polyolefinbackbone using particular perester free radical initiators for the graftpolymerization. When these .initiators are employed to prepare dyeablepolyolefin compositions, and particularly dyeable polypropylenecompositions, excellent properties of the resultant dyed composition areobtained. Certain of these perester initiators are known in the art ashaving utility in the random polymerization of various vinyl monomers,and this teaching is described in West German Pat. No. 1,198,067. Butheretofore these peresters have not been described as efficient freeradical initiators for graft polymerization to produce dyeablepolyolefins.

SUMMARY OF THE INVENTION It is an object of this invention to graftpolymerize at least one ethylenically unsaturated monomer onto apolyolefin backbone using certain perester free radical graftpolymerization initiators. It is another object of this invention toprepare polyolefin compositions having improved dye affinity by thegraft polymerization of at least one monoethylenically unsaturated,heterocyclic, nitrogen-containing monomer onto a polyolefin backbonewherein high conversions of monomer to graft polymer is obtained. Stillanother object of this invention is to obtain a dyeable polyolefin graftcopolymer that is capable of being shaped into articles having excellentproperties. These and other objects of the invention are accomplished bygrafting at least one ethylenically unsaturated monomer onto apolyolefin backbone polymer wherein at least one monomer is amonoethylenically unsaturated, heterocyclic, nitrogencontaining monomer.

The graft polymerization is accomplished by using, as a graftpolymerization free radical initiator, a perester selected from thegroup consisting of t-butyl 2- ethyl perhexanoate, t-amyl 2-ethylperhexanoate, t-

butyl 3,5,5-trimethyl perhexanoate, t-amyl 3,5,5- trimethylperhexanoate, t-butyl 2-ethyl perbutyrate, tamyl 2-ethyl perbutyrate,t-butyl perisobutyrate and tamyl perisobutyrate.

The perester free radical initiators employed in this invention areparticularly efficient for the selective polymerization of ethylenicallyunsaturated monomers to graft polymers onto a polyolefin backbone.Higher ratios of graft polymerized monomers to non-graft polymerizedmonomers are obtained by using the perester free radical initiatorsdescribed in this invention compared to using initiators commonlyemployed in the'prior art.

DETAILED DESCRIPTION OF THE INVENTION The polyolefins employed as thebackbone polymer in the graft polymerization of this invention includepolymers which contain a major proportion (i.e., greater than 50%) ofpolyolefins derived from l-alkenes having from 2 to 8 carbon atoms andparticularly 3 to 6 carbon atoms. Such polyolefins, therefore, in-

clude polyethylene, polypropylene, ethylene propylene block copolymers,ethylene butene-l block copolymers, polybutene-l, poly(4-methylpentene-l poly (3-methylbutene-l and the like. The termpolyolefin as used herein is, furthermore, intended to includecopolymers of l-alkene monomers with other copolymerizable monomers thatconstitute a minor proportion of the copolymer. Particularly usefulpolyolefin backbone polymers are those that are substantiallycrystalline polymers derived from l-alkenes having from 3 to 8 carbonatoms i.e., polymers containing at least 25 percent, and preferably atleast 50% crystallinity as determined by density-crystallinityrelationships, a type of technique described by J. A. Gailey et al., SPETechnical Papers (ANTEC), Vol. IX, Session IV-l pages 1 to 4, February1963. The polyolefin base polymer may be in any physical form convenientfor the graft polymerization process such as a powder, filament, pellet,fabric, etc.

In the graft copolymerization any monoethylenically unsaturated monomermay be grafted onto the polyolefin substrate and preferably at least oneof the grafted monomers is a monoethylenically unsaturated,heterocyclic, nitrogen-containing monomer. Representative heterocyclic,nitrogen-containing monomers are vinyl pyridines, vinyl morpholinonesand vinyl lactams such as vinyl pyrrolidones, N-vinyl succinimides andN- vinyl caprolactams. Examples of particular vinyl pyridines include2-vinyl pyridine, 3-vinyl pyridine, 4- vinyl pyridine, 5-methyl-2-vinylpyridine, 5-ethyl-2- vinyl pyridine, 2-methyl-5-vinyl pyridine,2-ethyl-5- vinyl pyridine, 2-methyl-6-vinyl pyridine, 2-ethyl-6- vinylpyridine, 2-isopropenyl pyridine, 5-propyl-2-vinyl pyridine and2,4-dimethyl-6-vinyl pyridine. Vinyl morpholinones includeN-vinyl-3-morpholinone, N- vinyl-S-methyl-3-morpholinone,N-vinyl-2-methyl-3- morpholinone, N-vinyl-5-phenyl-3-morpholinone andthe like.

Useful vinyl lactams include N-vinylpyrrolidones such asN-vinyl-Z-pyrrolidone itself, N-vinyl-S-methyl- Z-pyrrolidone,N-vinyl-3,3-dimethyl-2-pyrrolidone, N-

vinyl-4,4-dimethyl-2-pyrrolidone; N-vinylpiperidones such asN-vinyl-2-piperidone, N-vinyl-6-methyl-2- piperidone,N-vinyl-3,S-dimethylpiperidone and N- vinyl-caprolactam. Otherheterocyclic, nitrogen-containing monomers are N-vinyl piperidine,2-vinyl piperidine, 4-vinyl piperidine, N- vinyl phthalimide and N-vinylc'arbazole.

Ethylenically unsaturated monomers that may be I graft polymerized ontothe polyolefin base polymer either individually or together with anethylenically unsaturated, heterocyclic, nitrogen-containing monomerinclude styrenes, vinyl toluenes, ethylenically unsaturated carboxylicacid esters, vinyl esters, ethylenically unsaturated nitriles, vinylhalides, vinylidene halides, vinyl ethers, vinyl ketones, ethylenicallyunsaturated amines and ethylenically unsaturated carboxylic amides.Preferred monomers within the aforementioned classes of compounds arestyrene, alpha-methyl styrene, vinyl-o,m, or p-toluene, acrylonitrile,methacrylonitrile, vinyl chloride, vinylidene chloride, alkylacrylic-and alkyl methacrylic esters wherein the alkyl portion contains1 to 8 carbon atoms such as methyl acrylate, ethyl acrylate, butylacrylate, methyl methacrylate, butyl methacrylate, dimethylaminoethylmethacrylate, t-butylaminoethyl methacrylate, vinyl acetate, vinylpropionate, vinylethyl ether, vinyl nbutyl ether, vinyl isobutyl ether,vinyl 2-chloroethyl ether, vinyl methyl ketone, vinyl ethyl ketone,vinyl butyl ketone, acrylamide and methacrylamide.

The graft polymerization reaction is performed with a perester freeradical initiator such as t-butyl 2-ethyl perhexanoate, t-amyl 2-ethylperhexanoate, t-butyl 3,5,5-trimethyl perhexanoate, t-amyl3,5,5-trimethyl perhexanoate, t-butyl 2-ethyl perbutyrate, t-amyl 2-ethyl perbutyrate, t-butyl perisobutyrate and t-amyl perisobutyrate. Thepreferred graft polymerization initiator is t-butyl 2-ethyl perhexanoate(occasionally named t-butyl peroctoate" or t-butyl peroxy 2-ethylhexanoate). The perester graft polymerization initiators employed inthis invention are known compounds. The perester initiator may beprepared in high yields by the reaction of any acyl halide, particularlyan acyl chloride, with a hydroperoxide. For instance, t-butyl 2- ethylperhexanoate may be prepared by reacting 2- ethyl hexanoyl chloride witht-butyl hydroperoxide in the presence of an alkali metal hydroxide suchas sodium hydroxide.

The amount of graft polymerization initiator may vary from about 0.05percent to about percent or more, preferably 0.1 percent to about 3percent by weight, based on the total weight of added polymerizablemonomers. Amounts of free radical initiator in excess of 5 percent arenot considered economical. The graft polymerization initiators employedin this inven tion are particularly efficient in selectivelypolymerizing the added polymerizable monomers to graft polymers onto thepolyolefin substrate and thereby minimizing theamount ofhomopolymerization or random copolymerization of the added polymerizablemonomers. This results in a high ratio of graft polymerized monomers tonon-graft polymerized monomers. The term non-graft polymerized monomers"is intended to define the added polymerizable monomers that polymerize Iby mechanisms other than graft polymerization.

Graft polymerization is accomplished in any desired manner by knowngraft copolymerization tchniques.

The monomer or monomers to be graft polymerized may be diluted in asolvent together with the polymerization initiator and this mixtureadded to the reaction medium containing a polyolefin backbone polymerwhich may be in a finely-divided powder form such as a fiber orfilament.

A preferred form of graft polymerization is an aqueous dispersiontechnique wherein a pulverulent polyolefin is dispersed in an aqueoussolution containing a surface active agent and then the monomer ormonomers to be graft polymerized together with the free radicalinitiator are introduced in any way desired to the reaction medium. Themonomer, singly or in combination with one or more other ethylenicallyunsaturated polymerizable monomers as well as the graft polymerizationcatalyst, may be added to the reaction vessel by incremental additionfrom time to time mall at once as a single charge. The graftpolymerization is generally conducted at a temperature in the range ofabout 30 to 120 or more C., but generally in the range of about to C. Ifnecessary, supra-atmospheric pressures may be used to maintain theliquidphase. The time of polymerization is not critical and may vary fromabout 10 minutes to 4 or more hours.

If the graft polymerization units accomplished by an aqueous dispersiontechnique wherein 'the substrate polymer powder is dispersed in anaqueous medium, the dispersing agent or surfactant may be nonionic,

anionic or cationic. Preferred surfactants are the nonionicalkylphenoxypolyalkoxyalkanols having alkyl groups from about 7 to 18carbon atoms and 6 to 60 or more alkoxy unijs such asheptylphenoxypolyethoxyethanols, octylphenoxypolyethoxyethanols, andnonylphenoxypolyethoxyethanols.

After the graft copolymerization reaction, unreacted monomer may beremoved from the reaction vessel by washing the product or by vacuumdistillation. The grafted polyolefin may be removed from the reactionvessel, washed thoroughly with water and dried. Then the reactionproduct may be placed in a solvent for the non-grafted polymerizedmonomers such as ethanol, dimethylformamide or methyl ethyl ketone whichselectively extracts any non-grafted polymerized monomers. Thereafterthe reaction product is recovered, washed with water and dried in anoven. The dyeable polyolefin compositions are now ready for dye bathtreatment and fabricating into the desired form.

Filaments can be spun from the graft polyolefin compositions byconventional spinning techniques. The graft compositions can be meltspun or solution spun and the filaments can then be stretched to orientthe molecules and develop the desired tensile strength to the products.After shaping the graft compositions onto the filaments for otherdesired forms, dyeing with acid, pre-metallized or disperse dyes may beaccomplished.

For purposes of illustrating the invention, the follow ing examples areprovided wherein, unless otherwise indicated, all parts and percentagesare by weight.

EXAMPLE 1 In a polymerization vessel equipped with a stirrer, athermometer, inlet and outlet tubes for inert gas, and a device foradmitting reactants, a solution of 1250 ml. of distilled watercontaining 1.60 g. of t-octylphenoxypolyethoxyethanol having an averageof 10 ethoxy groups as a surfactant was introduced. The mixture washeated to 90C. and nitrogen was bubbled through while stirring todeaerate the system. Thereafter 500 g.

of 764 parts of a crystalline polypropylene-powder having a flow rate of4.9 (ASTM-D-l238-62T), 21.0 parts of 4-vinyl pyridine and 2.6 parts ofstyrene were charged together with 0.5 percent, based on the weight ofthe 4-vinyl pyridine and styrene monomers, of tbutyl 2-ethylperhexanoate. Heating at 90C. was continued for one hour and at the endof this time the grafted polypropylene powder was removed by filtration,washed thoroughly with water and dried in a vacuum oven.

The total conversion of the 4-vinyl pyridine and styrene monomers topolymer was 87 percent. Nongrafted polymerized monomers were extractedwith dimethylformamide in a Soxhlet apparatus. Analysis indicated that68 percent of the charged monomers (78 percent of the polymerizedmonomers) were present in the reaction product as graft polymers. Theratio of graft polymerized monomers to non-graft polymerized monomerswas 3.6 to 1. Thus t butyl 2-ethyl perhexanoate was a very efficientcatalyst for graft polymerization.

An inhibitor system comprising 0.1 percent (based on the weight ofpolypropylene) of 2,6-ditertiarybutyl 4-methy1 phenol, 0.5 percentdilauryl thiodipropionate and 0.15 percent calcium stearate was blendedinto the dry grafted polymer powder and the mixture was passed throughan extruder and pelletized. After melt spinning the fibers, the graftedpolypropylene was prepared for dye bath treatment.

Prior to dyeing, the fiber was prescoured in an aqueous solution of 1.0percent (OWF) of t-octylphenoxypolyethoxyethanol having an average ofethoxy units and 1.0 percent (OWF) soda ash for about 30 minutes at 82C.The abbreviation OWF means on the weight of the fiber or article.Thereafter the fiber was dyed in an aqueous dye bath containing 2percent (OWF) Capracyl Red G (Du Pont), a neutral premetallizeddyestuff, and then washed for minutes at 60C. in an aqueous solution (if1.0 percent (OWF) toctylphenoxypolyethoxyethanol having an average of 10ethoxy units. The fibers were dyed to a deep red shade.

Evaluation of the dyed fiber showed excellent light fastness, washresistance and dry cleaning resistance properties.

EXAMPLE 2 For comparative purposes, this example employs conventionalgraft polymerization initiators.

a. Using the apparatus described in Example 1 and following the sameprocedure, a graft copolymer was prepared from 76.4 parts of thecrystalline polypropylene polymer described in Example I, 28.0 parts of4-vinyl pyridine and 3.5 parts of styrene as the reactants and a mixtureof 0.5 percent of lauryl peroxide and 0.10 percent of benzoyl peroxideas the graft polymerization catalysts. After polymerization, the totalconversion of monomers to polymer was 90%. Analysis indicated that 38percent of the charged monomers were present as a graft polymer. Theratio of grafted polymerized monomers to non-grafted polymerizedmonomers was 0.73 to 1. Although the total conversions of vinyl pyridineand styrene to polymers in Examples 1 and 2(a) were similar, the tbutyl2-ethyl perhexanoate of Example 1 was unexpectedly superior as a graftpolymerization initiator to enable a high percentage of monomers to beselectively converted to graft polymers.

b. Example 2(a) was repeated except that the monomer charge was equallydivided into 5 incremental additions spaced 15 minutes apart. The totalconversion of 4-vinyl pyridine and styrene to polymer was 91 percent, ofwhich 47 percent was present as graft polymer. The ratio of graftpolymer to non-graft polymer was 1.1 to l.

c. In another run using the same apparatus and procedure described inExample 2(a) above with the exception that the graft polymerizationinitiator was lauryl peroxide in an amount of 1.64 percent, based on theweight of the monomers, the total conversion was calculated as 88percent of which 29 percent represented the amount of charged monomersconverted to graft polymer. Therefore, the ratio of graft polymerizedmonomers to non-graft polymerized monomers was 0.49 to 1. This resultwas further evidence of the superior efficiency of t-butyl 2-ethylperhexanoate as a graft polymerization initiator.

Example 3 The graft polymerization technique of Example 1 was repeatedby adding a single charge, 68.5 parts of the same crystallinepolypropylene of Example 1, 28.0 parts of 4-vinyl pyridine, 3.5 parts ofstyrene and 0.5 percent, based on the weight of 4-vinyl pyridine andstyrene, of t-butyl 2-ethyl perhexanoate. Polymerization was conductedat a temperature of 90C. for one hour. Total conversion of monomers topolymer was 87 percent and percent of the charged monomers were graftpolymerized. Thus, the ratio of graft polymerized monomers to non-graftpolymerized monomers was 3.0 to 1.

Example 4 The procedure of Example 1 was followed except that 65.0 partsof the crystalline polypropylene described in Example 1, 17.5 parts of4-vinyl pyridine and 17.5 parts of styrene were charged together with0.5 percent of t-butyl 2-ethyl perhexanoate as polymerization initiator.After heating the reaction mixture for one hour at C., the totalconversion of monomers to polymers was found to be 96 percent. It wasdetermined that 66 percent of the charged 4-vinyl pyridine and styrenemonomers were present as grafted polymer and the ratio of graftpolymerized monomers to non-graft polymerized monomers was 2.2 to lExample 5 Using the same apparatus as in Example 1 and the samepolymerization procedure, the following reactants were charged to thepolymerization vessel containing 1250 m1. of distilled water containing1.60 g. of a nonionic t-alkylphenoxypolyethoxyethanol surfactant: 500 g.of 76.4 parts of crystalline polypropylene described in Example 1, 21.0parts of 2-methyl-5-vinyl pyridine and 2.6 parts of styrene.Polymerization was conducted at 90C. for a period of one hour using 0.5

percent, based on the total weight of the charged monomers, of t-butyl2-ethyl perhexanoate as the free radical initiator for thegraftpolymerization. The total conversion of monomers to polymer wascalculated as 91 percent of which 62 percent of the charged monomers (or68 percent of the polymerized monomers) were present as grafted polymer.Therefore, the ratio of graft polymerized monomers to nongraftpolymerized monomers was 2.1 to 1.

Example 6 In the apparatus described in Example 1, 382 g. of thecrystalline polypropylene described in Example 1 were charged to thereaction vessel containing 1250 ml. of a solution of distilled water and1.60 g. of t-octylphenoxypolyethoxyethanol as a surfactant. Stirringdispersed the polypropylene powder throughout the solution and then amonomer charge of 105 g. of 4- vinyl pyridine and 13 g. of styrenetogether with 0.5 percent, based on the total weight of the monomers, oft-butyl 2-ethyl perhexanoate were incrementally introduced into thepolymerization vessel in equal additions spaced 15 minutes apart whilethe temperature in the reaction vessel was maintained at 90C. Theheating was continued for one hour after the final monomer addition. Thegraft polymer was recovered by the procedure described in Example 1. Thetotal conversion of monomer to polymer was 84 percent and the conversionof charged monomers to graft polymerized monomers was 64 percent. Theratio of graft polymerized monomers to non-graft polymerized monomerswas calculated as 3.2 to 1.

Example 7 The graft polymerization procedure of Example l was repeatedwith the exception that 2-methyl-5-vinyl pyridine was substituted for4-vinyl pyridine but the same amount of styrene was employed. Afterpolymerizing for one hour at 90C., the graft copolymer was recovered andsimilar conversions to graft copolymer were obtained.

Example 8 Example 9 Using the apparatus and following the proceduredescribed in Example I, 70 parts of the crystalline polypropylenedescribed in Example 1 were charged to a reaction vessel containing anaqueous solution and a surfactant to disperse the polypropylene. Whilestirring, a monomer charge of 15 parts of N-vinyl-Z-pyrrolidone and 15parts of methyl acrylate was added together with 1.5 percent, based onthe total weight ofthe monomer, of t-butyl 3,5,5-trimethyl perhexanoate.Good conversions to graft copolymer were obtained.

This. example was repeated using 0.5 percent of tamyl 2-ethylperhexanoate as the graft copolymerization initiator and highconversions to graft copolymer were observed.

Example 10 7 In the polymerization apparatus of Example 1 and using thesame procedure, 67.0 parts of pulverulent crystallinepolypropylene'described in Example 1, 17.5 parts of 2-methyl-5-vinylpyridine and 15.5 parts of 4- vinyl pyridine together with 0.5 percentof t-butyl 2- ethyl perhexanoate were charged while the reactiontemperature .was maintained at C. for one hour. A total conversion ofmonomer to polymer of 73 percent was obtained and 54 percent of thecharged monomers were converted to graft copolymer. Therefore, the ratioof graft polymerized monomer to non-graft polymerized monomer was 2.8 tol.

The above example was repeated except that the free radical initiatorwas t-butyl perisobutyrate and goo conversions were obtained.

Example 1 1 Example 1 was repeated except that the alpha-olefin polymerwas a propylene-ethylene terminal block copolymer having a flow rate of4.0 and the free radical initiator was t-amyl perisobutyrate. Goodconversions to graft copolymer'were obtained.

Upon repeating the above example with t-amyl 2- ethyl perbutyrate as thefree radical initiator, similar conversions to graft copolymer wereobtained.

I claim:

1. In a process for the graft polymerization of at least oneethylenically unsaturated monomer onto a polyolefin wherein saidpolyolefin is derived from l-alkenes having from 2 to 8 carbon atoms,the improvement wherein the free radical initiator for the graftpolymerization is a perester selected from the group consisting oft-butyl 2-ethylperhexanoate, t-amyl 2- ethylperhexanoate, t-butyl3,5,5-trimethylperhexanoate, t-amyl 3,5,S-trimethylperhexanoate, t-butyl2- ethylperbutyrate, t-amyl 2-ethylperbutyrate, t-butyl perisobutyrateand t-amyl perisobutyrate, the amount of said perester being about 0.05%or more, based on the weight of said monomer.

2. A process according to claim 1 wherein at least two differentmonoethylenically unsaturated monomers are graft polymerized onto apolyolefin, one of said monomers being a monoethylenically unsaturated,heterocyclic, nitrogen-containing monomer selected from the groupconsisting of vinyl pyridines, vinyl morpholinones and vinyl lactams.

3. A process according to claim 2 wherein said monoethylenicallyunsaturated, heterocyclic, nitrogencontaining monomer is a vinylpyridine.

4. A process according to claim 3 wherein said pyridine is selected fromthe group consisting of 4-vinyl pyridine and 2-methyl-5-vinyl-pyridine.

5. A process according to claim 1 wherein said polyolefin ispolypropylene and said peresteris t-butyl 2-ethylperhexanoate.

6. A process according to claim 1 wherein said ethylenically unsaturatedmonomer is a vinyl pyridine and said perester is t-butyl2-ethylperhexanoate.

7. A process according to claim 1 wherein said polyolefin ispolypropylene.

10. A process according to claim 1 wherein said polyolefin ispolypropylene, said perester is t-butyl 2- ethylperhexanoate and theamount of said perester may vary from about 0.1 percent to about 3percent by weight, based on the total weight of said ethylenicallyunsaturated monomer.

g g UNITED STATES PATENT OFFICE 5 9 *n rm 7; {3E 'iIFECATn O35 CORREQ116m Patent No. 3,728, n7 y Dated April 17, 973

Inventor(s) Donald aack It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 1, line 5: "ozf should 'be for 001mm 1, line 55: "is" should beare Column line 25: "units" shouldbe i Column line 32: "unijs" should.be units Column 5, line 32.", "the", first occurrence, should be intoColumn 9., line 5 up to and including line 8 should be canceled. Column10, line 1, "10" should read Signed and-sealed this 20th day of November1973.

(SEAL) Attest:

LEDWARD M.FLETCHER,JR. RENE o. TEG'I'MEYER Acting Commissioner ofPatents Attesting Officer

2. A process according to claim 1 wherein at least two differentmonoethylenically unsaturated monomers are graft polymerized onto apolyolefin, one of said monomers being a monoethylenically unsaturated,heterocyclic, nitrogen-containing monomer selected from the groupconsisting of vinyl pyridines, vinyl morpholinones and vinyl lactams. 3.A process according to claim 2 wherein said monoethylenicallyunsaturated, heterocyclic, nitrogen-containing monomer is a vinylpyridine.
 4. A process according to claim 3 wherein said pyridine isselected from the group consisting of 4-vinyl pyridine and2-methyl-5-vinyl-pyridine.
 5. A process according to claim 1 whereinsaid polyolefin is polypropylene and said perester is t-butyl2-ethylperhexanoate.
 6. A process according to claim 1 wherein saidethylenically unsaturated monomer is a vinyl pyridine and said peresteris t-butyl 2-ethylperhexanoate.
 7. A process according to claim 1wherein said polyolefin is polypropylene.
 8. A process according toclaim 1 wherein said polyolefin is polypropylene, one of said monomersis a vinyl pyridine and another of said monomers is styrene and saidperester is t-butyl 2-ethylperhexanoate.
 9. A process according to claim1 wherein the amount of said peRester may vary from about 0.05 percentto about 5 percent by weight, based on the total weight of saidethylenically unsaturated monomer.
 10. A process according to claim 1wherein said polyolefin is polypropylene, said perester is t-butyl2-ethylperhexanoate and the amount of said perester may vary from about0.1 percent to about 3 percent by weight, based on the total weight ofsaid ethylenically unsaturated monomer.